Clarifiers can be used for separating a variety of liquids from liquids, such as removing suspended hydrocarbon or oils from water, such as from tank farms, petroleum marketing facilities, refineries, utilities, gasoline stations, vehicle repair and maintenance shops, petrochemical plants, truck stops, parking lots, steel mills, storm water run off, surface run off, street wash waters, and the like. Various state and fedral cts and regulations prohibit discharge of any pollutants to U.S. navigable waters, pollution from natural storm water run off as well as elicit disposal in the storm sewer. Under current storm water regulations, drainage systems must be capable of removing contaminants, such as the ptroleum hydrocarbons, from storm water run off at least down to 15 pacts per million concentrations, which include the removal of all petroleum droplets equal to or greater than 20 microns in size.
Conventional methods of separating liquid droplets entrained in liquids, such as oil in water, and separating solids in liquids, include gravity separation, filtration, absorption, cohesion dispersion, air flotation, microbiological, electrolytic, physical, chemical, and coalescing methods.
The circular clarifier of the present invention is particularly suitable for gravity separation of entrained liquid droplets and solids from liquids, such as oil from water, solids from water, and oil and solids from water. The clarifier can be utilized as an oil-water separator, a primary settling tank in industrial waste applications, a secondary settling tank for biological treatment processes in domestic and industrial waste applications, and for the applications set forth above.
The following patents are illustrative of the state of the art developed in a preliminary search.
U.S. Pat. No. 3,966,617 discloses a tank with central feed, a rotating skimmer, and a peripheral collector.
U.S. Pat. No. 4,376,045. discloses a liquid treatment apparatus with a center feed, internal baffles, and an overflow weir.
U.S. Pat. No. 3,353,676 discloses a tank having a cone bottom, center feed, and a weir.
U.S. Pat. No. 5,158,679 discloses an oil/water separator with an oil scraper.
U.S. Pat. No. 5,047,151 discloses a scum skimming system for circular sedimentation tanks having a central feed and weir, but it also has a bottom scraper.
U.S. Pat. No. 5,015,392 discloses a thickener gravity separator with a cone bottom.
U.S. Pat. No. 4,983,294 discloses a separator with a cone bottom that uses fluid velocity to scrape the bottom or the tank.
U.S. Pat. No. 4,915,823 discloses an oil/water separator having a central feed.
U.S. Pat. No. 4,137,173 discloses a tank with a trap for grease dissolved or entrained in a liquid.
U.S. Pat. No. 3,770,131 discloses a feedwell centered in a sedimentation pool.
U.S. Pat. No. 3,717,257 discloses a tank with a rotating skimmer and a peripheral weir.
German Patent No. 718 547 discloses a clarifier with a center feed, cone bottom, and internal baffles.
None of the foregoing patents or circular clarifiers available at present disclose the clarifier of the present invention, its mode of operation, or the methods of the present invention and their advantageous results.